Abstract: Objective　To evaluate the biosafety of four different disinfectants applied to microbial contamination control in DUWLs. Methods The cytotoxicity of four different disinfectants (hydrogen peroxide nano silver ion, sodium hypochlorite, hydrogen peroxide, chlorhexidine) on human oral mucosal epithelial cells under different concentrations in vitro and the biosafety of different disinfectants were studied and compared by CCK-8. Results The four disinfectants all produced cytotoxicity after being treated with human oral epithelial mucosal cells for a certain period of time under the common disinfection concentration. However, the toxicity grades of 0.2% hydrogen peroxide nano silver ion and 0.2% chlorhexidine were medium toxicity (Grade 2), the toxicity grades of 5.25% sodium hypochlorite and 3% hydrogen peroxide were severe toxicity (Grade 4). Conclusion The cytotoxicity of different disinfectants in vitro is different. Hydrogen peroxide nano silver ion and chlorhexidine are less toxic to cells than the sodium hypochlorite and hydrogen peroxide under the common concentration of water pollution control in dental unit waterlines and are relatively safe.

Key words: waterline pollution, biosafety, cytotoxicity